Control lever apparatus and actuator operation apparatus

ABSTRACT

A switch mechanism 70 discriminates as to whether a lever 40 is in a detent position or not. When the lever is in the detent position, a detent device 80 is activated by a fluid pressure to produce a force for holding the lever in the detent position. The operation of the detent device is dismissed when the lever is not in the detent position. A pressure sensor 97 detects whether the operator&#39;s hand is in touch with the grip 49 of the lever, thus determining whether the operation of the detent device 80 is necessary. An actuator 30 is operated or stopped in response to manipulation of the lever. When the lever is moved to a position other than the detent position, an operation reaction force of a level corresponding to the load pressure in the actuator is applied by reaction force device 60, 60&#39; to the lever so as to enable the operator to sense any change in the load pressure and starting operation of the actuator. When the lever is in the detent position, the reaction force device 60, 60&#39; does not operate so as to enhance the efficiency of the operation of the detent device 80 for holding the lever.

This is a division of application Ser. No. 07/433,170, filed on Nov. 8,1989, now U.S. Pat. No. 5,058,451 issued on Oct. 12, 1991

BACKGROUND OF THE INVENTION

2. Field of the Invention.

The present invention relates to a control lever apparatus and anactuator operation apparatus which are for use in construction equipmentsuch as a crane. More particularly, the present invention is concernedwith a control lever apparatus having a detent device which is capableof holding the lever at a switching operation position and also relatesto an actuator operation apparatus having a reaction force devicecapable of imparting to the lever an operation reaction force of a levelcorresponding to the load pressure acting on the actuator.

2. Discussion of the Background

Japanese Utility Model Laid-Open No. 55-14199 discloses an operationapparatus which is provided with a reaction force device which impartsan operation reaction force of a level corresponding to the load on ahydraulic motor of a crane for lifting and lowering a load in order toenable the operator to sense the movement of the load handled by thecrane.

On the other hand, Japanese Utility Model Laid-Open Publication Nos.61-190620 and 190621 disclose a control lever apparatus having a detentdevice which is composed of a potentiometer and a torque motor forholding the control lever at a desired operational position.

The operation apparatus disclosed in Japanese Utility Model Laid-OpenNo. 55-14199 has a pilot lever operated through a lever. The pilot valveproduces a pilot pressure of a level corresponding to the operation ofthe lever, so that a pilot-type control valve is switched by the pilotpressure. As a result of switching of the control valve, a pressurizedfluid is supplied to a hydraulic motor for operating a winch so as toactuate the hydraulic motor. The hydraulic motor in turn drives a winchdrum connected to the rotor of the hydraulic motor so as to lift orlower a load. Meanwhile, the hydraulic load pressure acting in the motoris introduced to a chamber in a reaction force cylinder, throughconduits communicating with ports on both sides of the hydraulic motorand through a pilot conduit. The reaction force cylinder is connected tothe pilot valve. The load pressure introduced into the above-mentionedchamber acts to push a piston in the reaction force cylinder and a rodconnected to the piston. The rod is brought into contact with a camconnected to the lever so as to produce a force which acts to return thelever to the neutral position, i.e., an operation reaction force. Thisoperation reaction force is proportional to the load pressure acting inthe hydraulic motor, so that the operator operating the lever can sensethe reactive force proportional to the load pressure in the hydraulicmotor. The operator therefore can feel the movement of the load throughsensing the change in the load pressure.

In this operation apparatus, however, the lever is returned to theneutral position unless the operator holds it against the reactionforce. Therefore, when lifting or lowering of the load is continued fora time period, the operator is obliged to hold the lever at an operativeposition against the reaction force.

On the other hand, the detent device for a control lever disclosed inJapanese Utility Model Laid-Open Publication Nos. 61-190620 and61-190621 has a potentiometer connected to a pivot shaft of the leverand a torque motor. The angle of rotation of the pivot shaft,corresponding to the amount of operation of the control lever, isconverted by the potentiometer into an electrical signal. Thiselectrical signal, representing the detected amount of operation of thecontrol lever, is compared with values set in a setting device in whichlever detent positions are set. The lever is provided with a detentcanceling switch. When the detent canceling switch is off while thelever is in the detent position, a position holding signal is deliveredto the torque motor so that the torque motor produces a torque necessaryfor holding the lever at the detent position. When the lever is set at aposition other than a detent position while the detent canceling switchif off, a reaction force signal is delivered to the torque motor so thatthe torque motor imparts an operational reaction force to the lever Whenthe detent canceling switch is on, the reaction force signal isgenerated over the entire range of the lever position so that the torquemotor imparts a predetermined level of reaction force to the leverregardless of whether or not the lever is in a detent position.

The detent device of the control lever of the type mentioned abovecontrols the torque motor in accordance with an analog detection signalderived from the potentiometer such that the torque motor controls theforce on the lever, i.e., the force for holding the lever at a detentposition and the operational reaction force Thus, the operation reactivefore is controlled in accordance with the angle or amount of operationof the lever, regardless of the load pressure in the actuator Inaddition, holding of the lever at a detent position tends to causehunting of the lever at the detent position due to fluctuation in theresponse of the torque motor.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a controllever apparatus which can automatically and securely holding a controllever at a detent position.

Another object of the invention is to provide an actuator operationapparatus which, when a control lever of a hydraulic actuator is set ata position other than detent positions, automatically controls theoperation reaction force on the controller in accordance with the levelof the load on the actuator, i.e., the level of the load pressure, so asto enable an operator to easily sense at his hand any change in the loadlevel and the start of movement of the load without fail.

Still another object of the invention is to provide an apparatus inwhich, when a lever has been moved to a detent position, operationalreaction force is automatically reduced to prevent the lever from movingout of the detent position, thus automatically holding the lever in thedetent position, while enhancing the response to the switching operationeffected at the detent position thereby suppressing the occurrence ofhunting.

To this end, according to the invention, there is provided a controllever apparatus comprising: a control lever rotatably supported on astationary member through a pivot shaft; a rotary member connected tothe lever and rotatable as a unit with the lever; a switch mechanismcapable of making a selection as to whether the lever is to be held in adetent position; a working fluid source; a detent device acting betweenthe stationary member and the rotary member and capable of operating bypressurized working fluid so as to hold the lever at the detentposition; and a control device for supplying, when the switch mechanismhas selected to hold the lever in the detent position, the pressurizedfluid from the fluid source to the detent device thereby to enable thedetent device to hold the lever in the detent position.

In the control lever apparatus of the invention, the rotary member isprovided on the surface thereof with a pair of arcuate cam surfacescentered substantially at the axis of the pivot shaft, and the detentdevice is provided between the stationary member and a detent positionon one of the cam surfaces, while the switch mechanism is disposedbetween the stationary member and the other of the cam surfaces, so thatthe switch mechanism and the detent device do not interfere with eachother.

In the control lever apparatus of the invention, the switch mechanism isprovided between the stationary member and the rotary member and iscapable of producing a detent position holding signal when the lever isin the detent position as well as a detent dismissal signal when thelever is in a position other than the detent position.

In the control lever apparatus of the invention, the switch mechanismincludes a cam surface provided in the rotary member and a ball which isheld in rolling contact with the can surface. The ball is rotatablycarried on an end of a sliding member which is slidably supported by thestationary member and urged by a spring to project towards the camsurface. The ball and the cam surface are made of electricallyconductive materials. The cam surface is provided on a detent positionwith an insulating member so that a switch of the switch mechanism isturned off to enable the switch mechanism to produce the detent positionholding signal when the lever has been moved to the detent position,while, when the lever is in a position other than the detent position,the switch is turned on to enable the switch mechanism to produce thedetent dismissal signal. When the lever is operated, the ball rolls onthe cam surface so as to reduce the resistance force of the switchmechanism against rotation of the lever.

The control lever apparatus of the invention has a detent device whichis operated by a pressurized fluid so as to make sure that the lever isheld in a detent position. The detent device includes a cylinder casefixed to the stationary member, a detent member slidably supported bythe cylinder case, a chamber formed behind the detent member and capableof receiving the pressurized fluid, a spring for urging the detentmember so as to project from the cylinder case, and a detent engagingportion provided on a detent position on the rotary member. An endportion of the detent member engages with the engaging portion when thelever is in the detent position. The detent member carries at its end aball rotatable thereon and makes rolling contact with the cam surface,while the detent portion of the cam surface is provided with a recessserving as the detent engaging portion.

In the control lever apparatus of the invention, there is provided acontrol device for controlling operation of the detent device. Thecontrol device includes a switching valve switchable in response to asignal from the switch mechanism between a detent operative positionwhere it passes the pressurized fluid from the fluid source to thedetent device and a detent dismissal position where it allows the fluidto be discharged from the detent device to a reservoir.

When the lever is in a detent position, the ball engages with the recessmentioned above. On the other hand, the switch mechanism delivers adetent position holding signal and, in response to this signal, thecontrol device allows the pressurized fluid to be supplied to thechamber of the detent device and the pressure of the pressurized fluidproduces a force which urges the detent member in a projectingdirection, whereby the ball engages with the recess with a large force.Therefore, the lever is securely held in the detent position even whenit is released from the operator's hand.

Conversely, when the lever is in a position other than the detentposition, the switch mechanism delivers a detent dismissal signal sothat the pressurized fluid in the chamber is communicated to a reservoirto reduce the pressure in the chamber. In this state, the ball is heldin rolling contact with the cam surface by the force of the springalone. The ball rolls on the cam surface when the rotary member rotatesin response to manipulation of the lever, so that the lever can bemanipulated smoothly with reduced resistance.

In the control lever apparatus of the present invention, the switchmechanism for enabling selection as to whether the lever is to be heldon the detent position may include a sensor capable of detecting whetherthe lever is being touched by an operator's hand. The sensor may be apressure sensor provided on the grip of the lever or a strain gaugecapable of detecting deflection of the lever.

In such an arrangement, the detent device never does operate insofar asthe lever is touched by the operator. The detent device is allowed tooperate to hold the lever in the detent position only when the lever isin a detent position and is not touched by the operator.

The actuator operation apparatus of the present invention has aconstruction which is substantially the same as that of the controllever apparatus. In addition to the feature of the control leverapparatus, the actuator operation apparatus of the invention includes areaction force device for imparting to the lever an operational reactionforce of a level corresponding to the state of operation of the actuatorwhen the lever is in a position other than the detent position.

Namely, the invention also provides an actuator operating apparatuscomprising: a control lever rotatably supported on a stationary memberthrough a pivot shaft; a rotary member connected to the lever androtatable as a unit with the lever; a pilot valve secured to thestationary member and capable of being operated by the rotary member; apilot-type control valve switchable by pilot pressure output from thepilot valve; a first fluid source; an actuator operable when suppliedwith a pressurized fluid from the first fluid source while discharging afluid therefrom, in response to switching operation of the controlvalve; detection means capable of detecting the state of operation ofthe actuator; a reaction force device provided between the stationarymember and the rotary member and capable of operating by the pressurizedfluid so as to produce a reaction force which acts to urge the leverback to a neutral position; a switch mechanism for enabling selection asto whether the lever is to be held in the detent position; a secondfluid source; a detent device provided between the stationary member andthe rotary member and operative by the pressurized fluid so as toproduce a force for holding the lever in a detent position; and acontrol device capable of controlling, in response to a signal from theswitch mechanism, the supply of the pressurized fluid from the secondfluid source to the detent device, as well as discharge of the fluidfrom the detent device, and capable of controlling in response to asignal from the switch mechanism detection means, the supply of thepressurized fluid from the second fluid source to the reaction forcedevice, as well as discharge of the fluid from the reaction forcedevice.

In the actuator operating apparatus of the present invention, the rotarymember is provided on the surface thereof with a pair of arcuate camscentered substantially at the axis of the pivot shaft and a reactionforce receiving portion orthogonally intersecting the cam surfaces, theswitch mechanism being provided between the stationary member and one ofthe cam surfaces, the detent device being provided between thestationary member and a detent position on the other of the camsurfaces, the reaction force device being disposed at a portion of thestationary member confronting the reaction force receiving portion. Theconstruction of the switch device and the detent device are materiallythe same as those of the switch mechanism and the detent device of thecontrol lever apparatus explained above. In order to impart to the leveran operation reaction force corresponding to the state of operation ofthe actuator, the actuator operation apparatus of the present inventionhas a detection device, a control device and a reaction force devicehaving the following features.

The detection device includes sensors connected to conduits leading toand from a pair of ports for supplying the pressurized fluid to theactuator and for discharging the fluid from the actuator.

The control device may include means for supplying the pressurized fluidfrom the second fluid source to the detent device while allowing thefluid to be discharged from the reaction force device to a reservoirwhen the detent position holding signal is produced by the switchmechanism, whereas, when the detent position holding signal is notproduced, the means for supplying pressurized fluid allows the fluid tobe discharged from the detent device to the reservoir while supplyingfluid to the reaction force device which has pressure corresponding tothe signal from the detection means.

The control device may include a switching valve switchable in responseto a signal from the switch mechanism between a detent operativeposition where it passes the pressurized fluid from the second fluidsource to the detent device and a detent dismissal position where itallows the fluid to be discharged from the detent device to a reservoir.

The control device may include a controller capable of receiving asignal from the switch mechanism and a signal from the detection meansand producing a control signal corresponding to the received signals,and an electromagnetic proportional reducing valve capable of producinga secondary pressure corresponding to the control signal from thecontroller and delivering the secondary pressure to the reaction forcedevice.

The reaction force device may include a cylinder connected to the pilotvalve and may be used for controlling the operation reaction force, apiston axially slidably received in the piston, and a rod connected tothe piston and arranged to oppose the reaction force receiving surfaceof the rotary member.

In the actuator operation apparatus of the present invention, when thelever is operated, the rotary member is rotated to operate the pilotvalve so that the pilot pressure delivered by the pilot valve switchesthe control valve, whereby the pressurized fluid is supplied to theactuator from the first fluid source thereby operating the actuator. Theactuator is, for example, a hoist hydraulic motor for a crane and has arotor connected to a winch drum so that the winch drum is driven by themotor to lift and lower a load.

During operation, if the lever is in a position other than the detentposition, the switch mechanism produces a detent dismissal signal sothat the detent device does not operate. However, the state of operationof the actuator is detected by the detection device which produced asignal for operation the reaction force device so that an operationreaction force of a level corresponding to the state of operation of theactuator is applied to the lever. The operation reaction force isaccurately controlled in this state because the detent device has beendismissed.

When the lever has been moved to a detent position, the switch deviceproduces a detent position holding signal so that the detent device isoperated by the fluid pressure to hold the lever in the detent position.If the reaction force device is operative in this state, it is necessaryto apply a high fluid pressure to the detent device in order to hold thelever in the detent position overcoming the operation reaction forceproduced by the reaction force device. According to the invention,however, the reaction force device does not operate when the lever is inthe detent position so that the lever can be securely held in the detentposition even when the detent mechanism is operated with a low fluidpressure.

The control lever apparatus and the actuator operation apparatus of thepresent invention offers the following advantages.

The control lever apparatus is capable of automatically and securelyholding the lever in the detent position. When the lever is in aposition other than the detent position, the detent device does notoperate so that the lever can be manipulated without being interferedwith by the detent device. When the lever is in the detent position, thedetent device operates by the fluid pressure so as to hold the leverwith a large force.

In an arrangement in which the switch mechanism for determining whetherthe lever is to be held in the detent position is constituted by asensor capable of detecting a touch of operator's hand with the lever,e,g., a pressure sensor or a strain gauge, the detent device neveroperates insofar as the operator grips the lever. The detent deviceautomatically becomes operative to hold the lever in the detent positionwhen the lever is released from the operator's hand.

In the actuator operation apparatus of the present invention, operationof an actuator is controlled by switching a control valve by means of apilot pressure delivered by a pilot valve which is operable through alever. When the lever is manipulated at a position other than the detentposition, an operation reaction force of a level corresponding to thelevel of the load pressure acting in the actuator is applied to thelever. In this state, the operation reaction force on the lever iscontrolled without allowing the detent device to operate, so that theoperation reaction force can be controlled accurately without beinginterfered with by the detent device. The operator can feel and realizeany change in the load pressure in the actuator and the start ofoperation of the actuator, through sensing a change in the operationreaction force applied to the lever. When the lever is moved to a detentposition, the detent device becomes operative to hold the lever. In thisstate, the reaction force device does not operate so that the reactionforce is automatically reduced to hold the lever in the detent positionwithout allowing the lever to undesirably move from the detent position.By using a combination of a controller, a switching valve and anelectromagnetic proportional reducing valve as the control device, it ispossible to enhance the speed of response to the switching of thecontrol conducted when the lever is in the detent position.

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A, 1B and 1C are illustrations of an embodiment of a controllever apparatus and an actuator operation apparatus of the presentinvention in different positions;

FIG. 2 is a chart showing the relationship between load pressure andoperation reaction force under a reaction force control in the operationapparatus of the present invention;

FIG. 3 is a flow chart of a control performed by the operation apparatusof the present invention;

FIG. 4 is an illustration of an embodiment in which a pressure sensor isprovided on a lever;

FIG. 5 is a sectional view taken along 5--5 of FIG. 4 of an example ofthe pressure sensor;

FIG. 6 is a sectional view taken along line 6--6 of the lever shown inFIG. 5;

FIG. 7 a sectional view similar to FIG. 5 but illustrating anotherexample of the pressure sensor; and

FIG. 8 is an illustration of an embodiment in which a strain gauge isprovided on a lever.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1A shows a control lever apparatus and an actuator operationapparatus which embody the present invention. The control leverapparatus of the invention has a lever 40, a switch mechanism 70, adetent device 80 and so forth, while the actuator operation apparatus ofthe invention has a pilot valve 50, a pilot-type control valve 20, areaction force device 60, 60', a control device for the reaction forcedevice, and so forth.

Referring to FIG. 1A, a main pump 10 serving as a fluid supply source iscapable of sucking a fluid from a reservoir 12 and delivering the sameto a control valve 20. The control valve 20 is adapted to be switched bya pilot pressure supplied through a pilot valve 50 so as to directpressurized fluid from the pump 10 to an actuator 30. Fluid dischargedfrom each end of the actuator 30 is returned to the reservoir 12. Theactuator 30 is a hydraulic motor and is connected to a winch drum of,for example, a crane. As the motor 30 operates, the winch drum is drivenso as to wind and unwind a cable thereby lifting and lowering a load.

The pilot valve 50 has a valve case 501 which accommodates a pair ofreducing valves 51,51' which are

the load, respectively. The reducing valves 51,51' have pressurechambers 54,54' corresponding to an input port 52, a return port 52' andoutput ports 53,53', and spools 56,56 slidably received in thesechambers 54,54' and provided with oil ports 55,55'. Springs 57,57' areloaded between the rear ends of the spools 56,56' and the valve case501. Push rods 58,58' are connected to front ends of the spools 56,56'through springs 59, 59'. A pilot pump 11 as a second fluid supply sourceis connected to the port 52, while the return port 52' is connected tothe reservoir 12. The output ports 53,53' are connected to a switchingpilot portion of the control valve 20 through pilot passages 21,21'.

The lever 40 for operating the pilot valve 50 is connected to a rotarymember 41 which is pivotally supported through a pivot shaft 44 on astationary member 43. The stationary member 43 is connected to the valvecase 501 of the pilot valve 50. Portions 42,42' formed on the lowersurface of the rotary member 41 at both ends thereof oppose the pushrods 58,58' of the reducing valves 51,51' so that the push rods 58, 58'are operated by the portions 42,42' when the lever 40 is pivoted aboutthe pivot shaft 44.

The rotary member 41 connected to the lever 40 is provided on both sidesthereof with cam surfaces 45,46. One of the cams 45 opposes theaforementioned switch mechanism, while the other cam surface 46 opposesthe aforementioned detent device 80.

The switch mechanism 70 is capable of detecting whether the lever 40 isin one of detent positions 47, 48 (see FIGS. 1B and 1C, respectively).The switch mechanism 70 is composed of a cylinder case 71 made of aninsulating material and fixed to the stationary member 43, a piston 72as a sliding member received in the cylinder case 71, and a spring 73for urging the piston 72 towards the cam surface 45. A ball 74 isrotatably held on the end of the piston 72. Thus, the spring 73 urgesthe piston 72 such that the ball 74 makes rolling contact with the camsurface 45. The ball 74 and the rotary member 41 having the cam surface45 are made of electrically conductive materials. The ball 74 iselectrically connected to a power supply 93 such as battery through arelay 74. The rotary member 41 is electrically grounded through amachine body. Insulating members 76,76' are provided on portions of thecam surface 45 corresponding to the lifting and lowering detentpositions.

According to this arrangement, when the lever 40 is in a position otherthan the detent positions, the ball 74 contacts the exposed portion ofthe cam surface 45 so that the ball 74 is electrically connected to therotary member 41, with the result that the switch is turned on toactivate the relay 94. As a result, a normally-closed contact 95 of therelay 94 opens to de-energize a solenoid of a switching valve 96,whereby the switching valve 96 is held at the illustrated position. Whenthe lever 40 is in a detent position, the ball 74 rests on theinsulating member 76 or 76' so that the ball 74 and the rotary member 41are electrically insulated from each other, with the result that theswitch is turned off to allow the relay 94 to de-energized. As a result,the normally closed contact 95 closes to allow the solenoid of theswitching valve 96 to be energized, whereby the switching valve is movedto the right position as viewed in the drawing.

The detent device 80 has a cylinder-based construction similar to theswitch mechanism 70. More specifically, the detent mechanism 80 has acylinder case 81 connected to a stationary member 43, a piston 82 as adetent member, and a spring 83 which urges the piston 82 towards the camsurface 46. A ball 84 is rotatably carried on the end of the piston 82.Thus, the spring 83 urges the piston 82 so as to keep the ball 84 inrolling contact with the cam surface 46. Recesses 86, 86' as detentengaging portions are provided in the portions of the cam surface 46corresponding to lifting and lowering detent positions. When the lever40 is in a detent position, the ball 84 engages with the correspondingrecess 86 or 86'. In this state, as a result of the switching of theswitching valve 96, pressurized fluid from the pump 11 is introducedinto the chamber 85 accommodating the spring 83, whereby the lever 40 isheld at a detent position 47 or 48.

The operation apparatus of the present invention is intended forapplying to the lever 40 an operation reaction force corresponding tothe state of operation of the hydraulic motor 30, and has the followingconstruction. In order to detect the state of operation of the hydraulicmotor 30, pressure sensors 91, 91' are connected to the lifting fluidsupply conduit 31 and lowering fluid supply conduit 31', respectively,so as to detect the pressures in the respective conditions, i.e.,theload pressure in the motor 30.

A controller 90 receives the load pressure in the motor 3 sensed by thepressure sensor 91 or 91', a set value set in a setting device 92 and asignal from the switch mechanism 70, and computes a reaction forcecontrol signal in the form of an electrical current which is deliveredto an electromagnetic proportional reducing valve 65.

The reaction force devices 60,60' are integrally incorporated in thevalve case 501 of the pilot valve 50. More specifically, the reactionforce devices 60, 60' have reaction force cylinder chambers formed inthe valve case 501 adjacent to the reducing valves 51,51', pistons 61,61' slidably received in the cylinder chambers, and rods 62,62'connected to the pistons 61, 61' and opposing the aforementionedportions 42,42' of the rotary member 41. Chambers 63,63' behind thepistons 61, 61' are supplied with a secondary pressure from anelectromagnetic proportional reducing valve 65 through conduits 64,64'so that the pistons 61, 61' and, hence, the rods 62,62' are projectedoutward thereby causing the operation reaction force on the lever 40 toact on the portions 42,42'.

FIG. 1A shows the apparatus in a state in which the lever 40 of thepilot valve 50 have been moved from the neutral position in the liftingdirection. As a result of the lifting operation, portion 42 of therotary member 41 pushes the push rod 58 of the lifting reducing valve 51so that the port 53 delivers to the pilot conduit 21 a pilot pressurecorresponding to the operation angle of the lever, so that the controlvalve 20 is switched to the lifting position by the pilot pressure. Asconsequence, the fluid discharged from the pump 10 is discharged asindicated by an arrow into the hydraulic motor 30 through the conduit 31and a counter-balance valve (not shown) provided in this conduit,whereby the hydraulic motor 30 operates forwardly to rotate the winchdrum (not shown) in the lifting direction thereby hoisting the load.

During this lifting operation, the pressure Pa in the lifting conduit 31connected to the hydraulic motor 30 is detected by the pressure sensor91 and, at the same time, the pressure Pb in the lowering conduit 32 isdetected by the pressure sensor 91'. The pressures Pa and Pb are inputto the controller 90. When the lever 40 is in a position other than thedetent position 47, the ball 74 of the switch mechanism 70 contacts anexposed portion of the cam surface 45 so that the ball 74 and the rotarymember 41 are electrically connected to each other, whereby the relay 94is activated to open its normally closed contact 95, while the solenoidof the switching valve 96 is de-energized to keep the switching valve 96at the illustrated position. At the same time, the operation signal ofthe relay 94, i.e., a signal generated by the opening of the contact 95,is input to the controller 90 as a signal indicating that the lever isnot in the detent position.

As will be understood from the foregoing description, when the lever 40is in a position other than the detent positions 47, 48, the controller90 computes the difference between the pressure levels Pa and Pb derivedfrom the pressure sensors 91 and 91', whereby the lifting load pressure(effective load pressure) is determined. Then, a reaction force controlsignal corresponding to the lifting load pressure is computed anddelivered to the electromagnetic proportional reducing valve 65 so as tocontrol the secondary pressure from this reducing valve 65. Thesecondary pressure is input to the chamber 63 of the lifting reactionforce device 60 so as to cause the rod 62 to project to urge the portion42 integral with the lever 40 thereby exerting the operation reactionforce on the lever 40.

FIG. 2 is a diagram snowing the relationship between the load pressurePa (Pa-Pb) in the hydraulic motor 30 and the operation reaction force Faproduced by the reaction force device. As will be seen from this Figure,the operation reaction force Fa is controlled in proportion to the loadpressure Pa(Pa-Pb) of the hydraulic motor 30, so that the reaction forceFa is small when the load is light and is large when the load is heavy.Thus, the operator can feel and realize the change in the loaded statethrough sensing the change in the reaction force Fa by his hand grippingthe lever 40. When the lever 40 is in a position other than the detentpositions 47, 48, the switching valve 96 is in the illustrated positionso that the chamber 85 of the detent device 80 is communicated with thereservoir 12 so that only a weak force produced by the spring 83 aloneis available as the force for holding the lever 40 in the detentposition by the detent device 80. Thus, the reaction force is controlledadequately without being influenced by the holding force produced by thedetent device 80.

When the lever 40 is moved to the lifting detent position 47, the ball74 of the switch mechanism 70 rests on the insulating member 76 so thatthe ball 74 and the rotary member 41 are electrically insulated fromeach other with the result that the relay 94 is energized to close itsnormally-closed contact 95, while the solenoid of the switching valve 96is energized to shift the switching valve 96 to the right as viewed inthe Figure, whereby the close signal of the contact 95 is input to thecontroller 90 as a detent position detection signal. In this state, theball 84 of the detent device 80 is located at a position correspondingto the detent engaging portion 86 and, at the same time, the pressurizedfluid from the pump 11 is introduced into the chamber 83 of the detentdevice 80 as a result of the switching of the switching valve 96. As aconsequence, the piston 82 is urged outward by the fluid pressure tocause the ball 46 to engage with the engaging portion 86 at apredetermined pressure, whereby the lever 40 is held at the detentposition 47 as a result of this engagement.

When the lever 40 is in this detent position 47, the hydraulic motor 30continues to operate in the winding direction while the control valve 20is held in the winding position. In addition, the detection signals fromthe pressure sensors 91, 91' are being received by the controller 90. Asa consequence, the reaction force control on the basis of the loadpressure is dismissed as a result of the receipt of the detent positionsignal 47 and a control signal corresponding to a value set in thesetting device 92 is delivered from the controller 90 to theelectromagnetic proportional reducing valve 65.

If a control value for nullifying the reaction force is set beforehandset in the setting device 92, a signal of zero level is delivered fromthe controller 90 to the electromagnetic proportional reducing valve 65when the lever 40 is in the detent position 47, so that the secondarypressure produced by the reducing calve 65 is reduced to zero, thusnullifying the reaction force produced by the reaction force device 60.Therefore, the lever 40 held in the detent position 47 is never forcedback to the neutral position but is securely held in the detent positionby the above-mentioned detent device 80. Thus, the lever 40 is kept atthe detent position so that the lifting operation of the hydraulic motor3 is continued even after the lever 40 is released from the operator'shand. This enables the operator to operate another level to controlanother actuator simultaneously. This feature is quite advantageousparticularly when operation of two or more actuators is to be controlledand, hence, contributes to improvement in the operation efficiency.

When the lever 40 is in the detent position 47, the difference betweenthe detent holding force produced by the detent device 80 and thereaction force produced by the reaction force device 60 actually servesas an effective holding force. Therefore, the signal delivered to theelectromagnetic proportional reducing valve 65, when the lever 40 is inthe detent position 47, need not always be zero. Thus, it suffices onlyto set a minimum reaction force control value in the setting device 92such that the reaction force produced by the reaction force device 60 inresponse to the load pressure is smaller than the detent holding forceof the lever 40 exerted by the detent device 80.

It is possible to use a variable setting device such as a volume as thesetting device 92 so that the set value may be changed freely dependingon the content of the work. Such an arrangement is particularly usefulwhen the crane is designed to have a vibrating function throughreplacement of an attachment. Namely, in such a case, the minimumreaction force control value set in the setting device 92 is reduced toprovide a large effective holding force at the detent position 47 sothat the lever 40 can be securely held in the detent position againstthe vibration generated during operation of the crane in the vibratorymode. On the other hand, when inching operation of the crane isconducted frequently, a greater value may be set in the setting device92 so that the effective detent holding force at the detent position 47is reduced so as to enable the operator to move the lever 40 out of thedetent position 47 with a small manual force, thus facilitating theinching operation and, hence, remarkably improving the maneuverability.

FIG. 3 is a flow chart showing the flow of the control performed by thecontroller 90 when a variable setting device is used as the settingdevice 92. Referring to this Figure, in Step #1,the load pressure in thehydraulic motor 30 is determined on the basis of the pressures Pa and Pbsensed by the pressure sensors 91, 91'. In Step #2, the control signal xto be delivered to the electromagnetic proportional reducing valve 65 iscomputed in proportion to the load pressure. Step #3 determines whetherthe lever 40 is in a detent position or not. If the answer is YES, i.e.,when the lever 40 is in one of the detent positions, the processproceeds to Step #4 in which the reaction force set value y setbeforehand in the setting device 92 is read. In Step #5, the controlsignal x computed in Step #2 is compared with the set value y. When thecondition x>y is met, an answer YES is given and the process proceeds toStep #6 in which the reaction force control signal is set to y, i.e.,the control value y set in the setting device 92 is delivered to theelectromagnetic proportional reducing value 65 as the reaction forcecontrol signal. Conversely, if NO is the answer to the question posed inStep #3, i.e.,when the lever 40 is in a position other than the detentposition, as well as when the answer in Step #5 is NO, i.e., when thecondition x>y is not met, the process proceeds to Step #7 in which thesignal x computed in Step #2 is delivered to the electromagneticproportional reducing valve 65 as the reaction force control signal.

Thus, the secondary pressure output from the electromagneticproportional reducing valve 65 is adequately controlled and is optimallycontrolled even when the value set in the setting device 92 is changed,thereby ensuring that the reaction force produced by the reaction forcecylinder 6 is maintained below the detent holding force exerted on thelever 40 by the detent device 80. This completely eliminates any riskfor the lever 40 being unintentionally returned to the neutral position.As a result, the lever 40 is automatically and securely held in thedetent position 47, thus enhancing safety.

A similar control is performed when the lever 40 is moved in thelowering direction to the lowering detent position 48, as well as whenthe lever 40 is used at a position other than the detent position toreceive substantial operation reaction force.

FIG. 4 illustrates an embodiment of the control lever apparatus in whicha pressure sensor is provided on the lever. More specifically, thisembodiment has a pressure sensor 97 provided on the grip 49 of the lever40. The pressure sensor 97 is a switch mechanism which allows aselection as to whether the lever 40 is to be retained in the detentposition. The pressure sensor 49 is turned on and off, respectively,whenever the grip 49 is touched by and released from contact with theoperator's hand regardless of whether the operator wears a glove. Thepressure sensor 97 is connected to the power supply 93 in series to therelay 94 which has a normally-closed contact 95 placed in the circuitfor the power supply to the solenoid of the switching valve 96. Thesolenoid is therefore energized and de-energized as the sensor 97 isturned on and off, i.e., as the operator's hand touches and leaves thelever, thus controlling the state of the switching calve 96.

In the embodiment shown in FIG. 1, the switch mechanism 70 is providedto face one of the cam surfaces 45 on the rotary member 41. In theembodiment shown in FIG. 4, however, the switch mechanism 70 facing thecam surface 45 is omitted because in this embodiment the pressure sensor97 on the lever 40 serves as a switch mechanism. In the embodiment shownin FIG. 4, a detent device 80 similar to the detent device 80 facing theother cam surface 46 is provided so as to face the cam surface 45.

As will be seen from FIGS. 5 and 6, the pressure sensor 97 includes aplurality of lead switches 971 provided on a plurality of portions ofthe grip 49 of the lever at a circumferential interval, a magneticmember 972 surrounding the switches 871, and a pressure receiving member973 which surrounds the magnetic member 972. When the operator touchesthe grip 49, pressure exerted by the operator's hand is received by thepressure receiving member 973 and is transmitted to the magnetic member873 thereby turning the lead switch 971 on. The above-mentioned force isreleased when the grip 49 is released from the operator's hand, so thatthe switch 971 is turned off.

FIG. 7 illustrates another example of the pressure sensor 97. Thepressure sensor 97 shown in FIG. 7 is of a type so-called cord switch.More specifically, this pressure sensor 97 has a switch element 974 madeof a conductive rubber the electrical resistivity of which drasticallychanges between MΩ and Ω in response to a pressure applied thereto. Theswitch element 974 is sandwiched between electrodes 975 and 976 whichare made of flat-woven wires. This structure is enveloped by an elasticsilicon rubber. Thus, the switch element is turned on and off as theoperator touches and releases the grip 49.

The pressure sensor 97 may be provided not only on the peripheralsurface of the grip 49 but also on the center or peripheral portion ofthe top surface of the grip 49.

In the embodiment having the pressure sensor 97, the pressure sensor 97is turned on or off as the operator grips or touches the grip 49 of thelever 40. As a result, the relay 94 is operated so as to open itsnormally-closed contact 95 so that the solenoid is de-energized. As aconsequence, the solenoid-actuated switching valve 96 is held at theillustrated position so that the pressurized fluid is introduced intothe chamber 85 of the detent device 80. In this state, the detent device80 exerts only a small force produced by the spring 83, so that theresistance against rotation of the lever 40 can be reducedadvantageously.

When the lever has been moved to a detent position where the ball 84 ofthe detent device 80 engages with the recess 86 to 86', the engagementis sensed by the operator's hand, so that the operator releases thelever 40. As a result, the pressure sensor 97 is turned off tode-energize the relay 94 so as to close the normally-closed contact 95,whereby the solenoid-actuated switching valve 96 is moved to the rightposition in the drawings. As a consequence, the pressurized fluid fromthe pump 11 is supplied to the chamber 85 of the detent device 80. Inthis state, the sum of the force produced by the spring 83 and the forcegenerated by the pressure acting in the chamber 85 is applied to ball 84so that the rotary member 41 and, hence, the lever 50 are held at thedetent position. In this embodiment, a greater retaining force isobtained for retaining the lever 40 at the detent position by virtue ofuse of the pair of detent devices.

As the operator grips the lever 40 at the grip 49, the retaining forceexerted by the detent devices 80 is dismissed without delay so that theball 84 can easily be separated from the recess 86 or 86' thereby toallow the lever to be manipulated.

FIG. 8 shows an embodiment incorporating a strain gauge provided in thelever. The lever 40 has a certain level of elasticity so that it isdeflected or elastically deformed whenever a manipulation force isexerted on the lever, including the state of being merely touched by thehand, regardless of whether the lever 40 is held stationary or moved. Inthe embodiment shown in FIG. 8, a strain gauge 98 attached to the lever40 and capable of detecting deflection of the lever 40 is used as theswitch mechanism for detecting whether the lever 40 is touched by theuser's hand or not.

The output signal from the strain gauge 98 is amplified by the amplifier981 and, when a predetermined amount of deflection of the lever 40 isdetected, a transistor 981 is turned on by the output of the amplifier981 so as to activate a relay 983. As a consequence, the normally-closedcontact 984 is opened to de-energize the solenoid of the electromagneticswitching valve 96. Numerals 985 and 986 denote input resistances of thetransistor 982. It will be understood that the arrangement shown in FIG.8 produces substantially the same effect as the arrangement of FIG. 4.

The control lever apparatus of the present invention can be used foroperating an actuator which does not require control of the operationreaction force. Although a hydraulic motor for driving a crane winch hasbeen specifically mentioned as an example of the actuator, the inventioncan be applied to various other types of actuators such as a hydraulicmotor or cylinder for a boom hoist, hydraulic cylinders for drivingboom, arm or bucket of a power shovel, and so forth.

The switch mechanism for selecting for conducting selection as towhether the lever is to be held at the detent position may be arrangedsuch that, contrary to the case of the embodiment shown in FIG. 1, atleast the cam surfaces of the rotary member are electrically insulatingand conductive members are provided only on the portions of the camsurfaces corresponding to the detent positions of the lever so that theswitch is turned on or off as the ball is moved into and out of contactwith the conductive member on the portion of the cam surfacecorresponding to the detent position.

Although the described embodiments employ two detent devices: one forlifting and one for lowering, this is only illustrative and theinvention can have additional detent devices which operate, for example,when the lever is in the neutral position or in 1st or 2nd speedpositions. Thus, the invention can be carried out with three or moredetent mechanisms.

In the described embodiments, the recesses serving as the detentengaging portions are formed in the cam surfaces of the rotary memberwhile the balls act as cooperating detent members are provided on thepistons. This arrangement may be modified such that balls or thespherical projections are provided on the cam surfaces for engagementwith recesses formed in the end surface of the piston.

What is claimed is:
 1. An actuator operating apparatus comprising:a control lever rotatably supported on a stationary member through a pivot shaft; a rotary member connected to said lever and rotatably as a unit with said lever; a pilot valve secured to said stationary member for being operated by said rotary member; a pilot-type control valve switchable by pilot pressure output from said pilot valve; a first fluid source; an actuator operable when supplied with a pressurized fluid from said first fluid source while discharging a fluid therefrom in response to a switching operation of said control valve; detection means for detecting the state of operation of said actuator; a reaction force device provided between said stationary member and said rotary member for operating by the pressurized fluid so as to produce a reaction force which acts to urge said lever back to a neutral position; a second fluid source; a detent device provided between said stationary member and said rotary member and operative by the pressurized fluid so as to produce a force for holding said lever in a first detent position; a switch mechanism for enabling selection as to whether said lever is to be held in said detent position; and a control device capable of controlling, in response to a signal from said switch mechanism, the supply of pressurized fluid from said second fluid source to said detent device, as well as discharge of the fluid from said detent device, and for controlling, in response to a signal from said switch mechanism detection means, the supply of pressurized fluid from said second fluid source to said reaction force device, as well as discharge of the fluid from said reaction force device.
 2. An actuator operating apparatus according to claim 1, wherein said rotary member is provided on the surface thereof with a pair of arcuate cams centered substantially at the axis of said pivot shaft and a reaction force receiving surface orthogonally intersecting said cam surfaces, said switch mechanism being provided between said stationary member and one of said cam surfaces, said detent device being provided between said stationary member and a second detent position on the other of said cam surfaces, said reaction force device being disposed at a portion of said stationary member confronting said reaction force receiving surface.
 3. An actuator operating apparatus according to claim 1, wherein the switch mechanism is provided between said stationary member and said rotary member for producing said first detent position holding signal when said lever is in said first detent position and a detent dismissal signal when said lever is in a position other than said first detent position.
 4. An actuator operating apparatus according to claim 1, wherein said rotary member has an arcuate cam surface centered substantially at the axis of said pivot shaft, and wherein said switch mechanism includes said cam surface and a ball which is held in rolling contact with said cam surface, said ball being rotatably carried on an end of a sliding member which is slidably supported by said stationary member and urged by a spring to project towards said cam surface, said ball and said cam surface being made of electrically conductive members, said cam surface being provided when at said first detent position with an insulating member so that a switch of said switch mechanism is turned off so as to enable said switch mechanism to produce said first detent position holding signal when said lever has been moved to said first detent position, while, when said lever is in a position other than said first detent position, said switch is turned on to enable said switch mechanism to produce said detent dismissal signal.
 5. An actuator operating apparatus according to claim 1, wherein said rotary member is provided on the surface thereof with a cam surface centered at the axis of said pivot shaft, said detent device includes a cylinder case fixed to said stationary member within which said first detent member is slidably supported, a chamber formed behind said first detent member for receiving said pressurized fluid, a spring for urging said first detent member so as to project from said cylinder case, and a detent engaging portion provided on said first detent position on said rotary member, and wherein an end of said first detent member engages with said engaging portion when said lever is in said first detent position.
 6. A control lever apparatus according to claim 5, wherein said rotary member is provided on the surface thereof with an arcuate cam surface substantially centered at the axis of said pivot shaft, said detent engaging portion including a recess formed in said first detent position in said cam surface, said first detent member rotatably carrying a ball at an end thereof which makes rolling contact with said cam surface, said ball being engageable with said recess when said lever is in said first detent position.
 7. An actuator operation apparatus according to claim 1, wherein said detection means includes sensors connected to conduits leading to and from a pair of ports for supplying said pressurized fluid to said actuator and for discharging said fluid form said actuator.
 8. An actuator operation apparatus according to claim 1, wherein said reaction force device includes a cylinder connected to said pilot valve for controlling the operation reaction force, a piston axially slidably received in said cylinder, and a rod connected to said piston and arranged to oppose said reaction force receiving surface of said rotary member.
 9. An actuator operation apparatus according to claim 1, wherein said switch mechanism includes a detection switch provided between said stationary member and said rotary member for producing a first detent position holding signal and a detent dismissal signal, respectively, when said lever is in said first detent position and when said lever is in a position other than said first detent position, and wherein said control device includes means for supplying the pressurized fluid from said second fluid source to said detent device while allowing the fluid to be discharged from said reaction force device to a reservoir when said first detent position holding signal is produced by said switch mechanism, whereas, when said first detent position holding signal is not produced, said means allows the fluid to be discharged from said detent device to said reservoir while supplying said reaction force device with fluid pressure corresponding to the signal from said detection means.
 10. An actuator operation apparatus according to claim 1, wherein said control device includes a switching valve switchable in response to a signal from said switch mechanism between said first detent position where it passes said pressurized fluid from said second fluid source to said detent device and said detent dismissal position where it allows the fluid to be discharged from said detent device to a reservoir.
 11. An actuator operation apparatus according to claim 1, wherein said control device includes a controller for receiving a signal from said switch mechanism and a signal from said detection means and for producing a control signal corresponding to the received signals, and an electromagnetic proportional reducing valve for producing a secondary pressure corresponding to said control signal from said controller and delivering said secondary pressure to said reaction force device. 